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|
(************************************************************************)
(* v * The Coq Proof Assistant / The Coq Development Team *)
(* <O___,, * INRIA - CNRS - LIX - LRI - PPS - Copyright 1999-2010 *)
(* \VV/ **************************************************************)
(* // * This file is distributed under the terms of the *)
(* * GNU Lesser General Public License Version 2.1 *)
(************************************************************************)
exception Empty = Stack.Empty
type 'a t = {
mutable stack : 'a list;
mutable context : ('a list * 'a list) option
}
let create () = { stack = []; context = None }
let push x s = s.stack <- x :: s.stack
let pop = function
| { stack = [] } -> raise Stack.Empty
| { stack = x::xs } as s -> s.stack <- xs; x
let tip = function
| { stack = [] } -> raise Stack.Empty
| { stack = x::_ } -> x
let to_list = function
| { context = None; stack = s } -> s
| { context = Some (a,b); stack = s } -> a @ s @ b
let to_lists = function
| { context = None; stack = s } -> [],s,[]
| { context = Some (a,b); stack = s } -> a,s,b
let find f s =
let a, s, b = to_lists s in
try List.find (fun x -> f x false) a with Not_found ->
try List.find (fun x -> f x true) s with Not_found ->
List.find (fun x -> f x false) b
let find_map f s =
let rec aux b = function
| [] -> raise Not_found
| x :: xs -> match f x b with None -> aux b xs | Some i -> i
in
let a, s, b = to_lists s in
try aux false a with Not_found ->
try aux true s with Not_found ->
aux false b
type ('b, 'c) seek = ('b, 'c) CSig.seek = Stop of 'b | Next of 'c
let fold_until f accu s =
let rec aux accu = function
| [] -> raise Not_found
| x :: xs -> match f accu x with Stop x -> x | Next i -> aux i xs in
aux accu s.stack
let is_empty = function
| { stack = []; context = None } -> true
| _ -> false
let iter f = function
| { stack = s; context = None } -> List.iter (fun x -> f x true) s
| { stack = s; context = Some(a,b) } ->
List.iter (fun x -> f x false) a;
List.iter (fun x -> f x true) s;
List.iter (fun x -> f x false) b
let clear s = s.stack <- []; s.context <- None
let length = function
| { stack = s; context = None } -> List.length s
| { stack = s; context = Some(a,b) } ->
List.length a + List.length s + List.length b
let focus s ~cond_top:c_start ~cond_bot:c_stop =
if s.context <> None then raise (Invalid_argument "CStack.focus");
let rec aux (a,s,b) grab = function
| [] -> raise (Invalid_argument "CStack.focus")
| x::xs when not grab ->
if c_start x then aux (a,s,b) true (x::xs)
else aux (x::a,s,b) grab xs
| x::xs ->
if c_stop x then a, x::s, xs
else aux (a,x::s,b) grab xs in
let a, stack, b = aux ([],[],[]) false s.stack in
s.stack <- List.rev stack;
s.context <- Some (List.rev a, b)
let unfocus = function
| { context = None } -> raise (Invalid_argument "CStack.unfocus")
| { context = Some (a,b); stack } as s ->
s.context <- None;
s.stack <- a @ stack @ b
let focused { context } = context <> None
|
